The present invention relates generally to a peripheral audio system such as may be used to monitor and manipulate signals from an audio source. More particularly, the invention relates to a peripheral audio system adapted to detect a tempo and beats of an audio signal from at least one audio source and provide a user a visual interface whereby the user can interactively manipulate the audio signal to perform audio and lighting effects.
Rhythm of music deals with movement and organization of a music piece as related to time, where rhythm is organized according to meter and tempo. While meter is regular reoccurring pulsation of equal length, grouped into measures of two or three beats and compounds of these basic units into longer measures, tempo is instead the speed at which a music piece or its parts are to be performed. Within a given music piece the tempo may vary considerably. A unit of time in music is called a beat, which must reoccur often enough to constitute a series. Because the beat is a unit of time, the beat may not be heard. It is sufficient that the beat be felt or sensed. The tempo or speed of the music piece is a number of beats over time which is expressed herein as beats per minute ("BPM"). Tempo is usually established with a clear assured beat, and the clear assured beat is usually the first beat of each musical measure and is known as a down-beat.
Disc Jockeys ("DJs") skilled in the art of beat mixing work extensively with matching beats of an audio signal to sounds and lighting effects. DJs often try to manipulate or match the sounds within one audio signal to either a sound of another audio signal or a lighting device to produce effects, such as strobe lights that pulse to the beat of a music piece. Another effect is to allow one part of the music piece to flow into another music piece by either having the one audio signal gradually fade into other audio signal, such as is done in a "beat-to-beat" mix. Another effect is to suddenly stop one music piece and start another so that beat flow is not interrupted, such as is done in a "slam" mix. To assist DJs in this task, DJs often use at least one audio peripheral device, such as a beat per minute ("BPM") counter, which provides the DJs with information on the BPM of the audio signal.
One such type of BPM counters is a manual hand-tapping calculators. The manual calculators output the BPM information manually entered by the DJs in a continual manner. However, one draw-back of the manual calculators is that they can not track tempo changes of the audio signal over time, and act more like metronomes.
A "disco beat meter" as described in U.S. Pat. No. 4,300,225 ("225' Patent") entitled "Disco Beat Meter" of George R. Lamb can track the beats of the audio signal as the tempo changes for some music. However, the 225' Patent is aimed at tracking the tempo of disco music. Specifically, the 225' Patent depends on a heavy bass beat, as is present in most disco music, to continue to track the tempo. If an instrument defining the beat is not a heavy bass beat of the drum, the invention of the 225' Patent can not pick up the beat. Further, if the beat is silent for several beats, the Disco Beat Meter defaults to a BPM of 120. Thus, the Disco Beat Meter may misrepresent the BPM of a music piece that has intermittent beats. Further, although the Disco Beat Meter takes two audio sources as input, it only displays when the beats are coincident with each other. This minimizes the ability of DJs utilizing the Disco Beat Meter to mix the beats and change the tempo appropriately.
Another such device entitled "The Don" manufactured by a British company called Intimidation includes an additional feature of a bar graph. This bar graph has 24 LED's total, 8 red LEDS for side 1, 8 green "mix" LEDS, 8 red LEDS for side 2. Each bar graph shifts or "marches" up 1 LED when the sound exceeds a threshold dialed in by the DJ. When the 2 bar graphs are matched, a green LED in the middle lights up where the two sides are coincident. The Don has draw-backs similar to the Disco Beat Meter in that it relies on a heavy, steady bass drum beat and can not track the tempo if the beat is given in other frequency ranges or by other instruments. In addition, as in the Disco Beat Meter if the beats are skipped or intermittently heard, The Don has difficulty tracking the bar graph. As such, the Disco Beat Meter and The Don are not very useful for music pieces that do not have either a disco beat or a steady bass drum beat, particularly when the beats are skipped or intermittently heard as is prevalent in newer music such as hip hop, country, rap, and alternative music.
One attempt to bypass these problems of tracking beats has been to concentrate on the tempo of the audio signal. For example, Pioneer Corporation produces a device that automatically tries to find the BPM also called the tempo of the music. This device provides no means of displaying how well the beats are matched. Mixing without properly matching the beats can produce galloping effects as the tempo may be properly mixed, but the beats are off set by an audible amount which results in a galloping sound. In addition, if a pattern of the music piece is a complex rhythm focusing on the tempo and ignoring the underlying beats may produce an inaccurate BPM.
Another prior art device embodied in a Numark Compact Disc ("CD") player also works best for beats as found in disco music and not in other types of music. Furthermore, the Numark CD player takes full control of the mixing from the DJ once the mixing functions are enabled.
There are also numerous digital samplers available on the market which enable DJs to record, play back, and loop several seconds of music almost instantly. A draw-back of these systems is that the few seconds of sound often can not be accurately captured and looped. Thus, off-line editing is often necessary to produce clean samples which are synchronized to the beat of the music.
Another peripheral device to control lighting devices was constructed so as to illuminate when the lighting devices received an audio signal of an appropriate sound level. One drawback with these lighting devices, however, is that they do not strobe with the beats but only strobe with a magnitude of the sound and accordingly often give unpredictable results. Further drawbacks of this system is its interface, which usually requires tedious manual manipulation. Alternatively, the lighting device is automated so that the DJ can not interactively work with the lighting device.
Accordingly it is an object of this invention to provide a peripheral audio system that can detect beats embodied in an audio signal other than a bass drum beat.
It is another object of this invention to provide a peripheral audio system that tracks the tempo as it is adjusted within the music source.
It is a further object of this invention to provide a peripheral audio system that can track the tempo of a music piece other than disco music.
It is still another object of this invention to provide an audio system that displays to a DJ when the beats of two music pieces are matched not just when a sound magnitude threshold is exceeded.
It is a further object of this invention to provide a peripheral audio system that can be interfaced with lighting devices and adapted to allow the lighting devices to strobe with the beats of a music piece.
It is still a further object of this invention to provide a peripheral audio system to allow DJs to interactively mix more than one audio signal.
It is a further object of this invention to provide a peripheral audio system that can interface with a sampler such that the sampler can accurately capture and loop portions of a music piece.
It is a further object of this invention to provide a peripheral audio system so that a DJ can perform mixing in real time and eliminate off-line editing.
These and other objects of the invention will be obvious and will appear hereinafter.